/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

/**
 * @author Alexey V. Varlamov
 */

package org.apache.harmony.security;

import java.net.URL;
import java.security.CodeSigner;
import java.security.CodeSource;
import java.security.Permission;
import java.security.Principal;
import java.util.Collection;
import java.util.Collections;

import org.apache.harmony.security.fortress.PolicyUtils;

/**
 * This class represents an elementary block of a security policy. It associates
 * a CodeSource of an executable code, Principals allowed to execute the code,
 * and a set of granted Permissions.
 * 
 * @see org.apache.harmony.security.DefaultPolicy
 */
public class PolicyEntry {

	// Store CodeSource
	private final CodeSource cs;

	// Array of principals
	private final Principal[] principals;

	// Permissions collection
	private final Collection<Permission> permissions;

	/**
	 * Constructor with initialization parameters. Passed collections are not
	 * referenced directly, but copied.
	 */
	public PolicyEntry(CodeSource cs, Collection<? extends Principal> prs,
			Collection<? extends Permission> permissions) {
		this.cs = (cs != null) ? normalizeCodeSource(cs) : null;
		principals = (prs == null || prs.isEmpty()) ? null : (Principal[]) prs
				.toArray(new Principal[prs.size()]);
		this.permissions = (permissions == null || permissions.isEmpty()) ? null
				: Collections.unmodifiableCollection(permissions);
	}

	/**
	 * Returns unmodifiable collection of permissions defined by this
	 * PolicyEntry, may be <code>null</code>.
	 */
	public Collection<Permission> getPermissions() {
		return permissions;
	}

	/**
	 * Checks if passed CodeSource matches this PolicyEntry. Null CodeSource of
	 * PolicyEntry implies any CodeSource; non-null CodeSource forwards to its
	 * imply() method.
	 */
	public boolean impliesCodeSource(CodeSource codeSource) {
		if (cs == null) {
			return true;
		}

		if (codeSource == null) {
			return false;
		}
		return cs.implies(normalizeCodeSource(codeSource));
	}

	/**
	 * Checks if specified Principals match this PolicyEntry. Null or empty set
	 * of Principals of PolicyEntry implies any Principals; otherwise specified
	 * array must contain all Principals of this PolicyEntry.
	 */
	public boolean impliesPrincipals(Principal[] prs) {
		return PolicyUtils.matchSubset(principals, prs);
	}

	/**
	 * Returns true if this PolicyEntry defines no Permissions, false otherwise.
	 */
	public boolean isVoid() {
		return permissions == null || permissions.size() == 0;
	}

	private CodeSource normalizeCodeSource(CodeSource codeSource) {
		final URL codeSourceURL = PolicyUtils.normalizeURL(codeSource
				.getLocation());
		CodeSource result = codeSource;

		if (codeSourceURL != codeSource.getLocation()) {
			// URL was normalized - recreate codeSource with new URL
			final CodeSigner[] signers = codeSource.getCodeSigners();
			if (signers == null) {
				result = new CodeSource(codeSourceURL,
						codeSource.getCertificates());
			} else {
				result = new CodeSource(codeSourceURL, signers);
			}
		}
		return result;
	}
}
